diff --git a/docs/unified_orbital_elements_plan.md b/docs/unified_orbital_elements_plan.md
index 5d4ede0..abea434 100644
--- a/docs/unified_orbital_elements_plan.md
+++ b/docs/unified_orbital_elements_plan.md
@@ -224,9 +224,9 @@ struct Spacecraft {
    - `config_loader.cpp`: Update parsing logic
    - `maneuver.cpp`: No changes needed
 
-### Phase 3: Update Config Parser
+### Phase 3: Update Config Parser ✅ COMPLETE
 
-7. **Modify config_loader.cpp - body parsing**
+7. ✅ **Modify config_loader.cpp - body parsing**
    - Remove old `position` field requirement from `parse_toml_body()`
    - Add `orbit` table parsing to `parse_toml_body()`
    - Parse all orbital element fields with defaults
@@ -234,12 +234,12 @@ struct Spacecraft {
    - Parse into `body->orbit` struct
    - Remove old `eccentricity` and `semi_major_axis` top-level fields
 
-8. **Modify config_loader.cpp - spacecraft parsing**
+8. ✅ **Modify config_loader.cpp - spacecraft parsing**
    - Replace `position` + `velocity` fields with `orbit` table parsing
    - Use same orbital element parsing logic as bodies
    - Parse into `craft->orbit` struct
 
-9. **Add validation for orbital elements**
+9. ✅ **Add validation for orbital elements**
    - `semi_major_axis` must not be zero
    - `eccentricity` must be >= 0
    - For elliptical orbits (e < 1): `semi_major_axis > 0`
diff --git a/src/config_loader.cpp b/src/config_loader.cpp
index 7d156df..3ca1508 100644
--- a/src/config_loader.cpp
+++ b/src/config_loader.cpp
@@ -59,36 +59,86 @@ static bool parse_toml_body(toml_datum_t body_table, CelestialBody* body) {
     toml_datum_t mass = toml_get(body_table, "mass");
     toml_datum_t radius = toml_get(body_table, "radius");
     toml_datum_t parent_idx = toml_get(body_table, "parent_index");
-    toml_datum_t eccentricity = toml_get(body_table, "eccentricity");
-    toml_datum_t semi_major = toml_get(body_table, "semi_major_axis");
 
     if (mass.type != TOML_FP64 || radius.type != TOML_FP64 ||
-        parent_idx.type != TOML_INT64 ||
-        eccentricity.type != TOML_FP64 ||
-        semi_major.type != TOML_FP64) {
+        parent_idx.type != TOML_INT64) {
         return false;
     }
 
     body->mass = mass.u.fp64;
     body->radius = radius.u.fp64;
     body->parent_index = (int)(parent_idx.type == TOML_INT64 ? parent_idx.u.int64 : (int)parent_idx.u.fp64);
-    body->orbit.eccentricity = eccentricity.u.fp64;
-    body->orbit.semi_major_axis = semi_major.u.fp64;
 
-    // Extract position vector
-    toml_datum_t position = toml_get(body_table, "position");
-    if (position.type != TOML_TABLE || !extract_vec3_from_table(position, &body->global_position)) {
+    // Parse orbit table
+    toml_datum_t orbit_table = toml_get(body_table, "orbit");
+    if (orbit_table.type != TOML_TABLE) {
+        printf("Error: Body '%s' missing required 'orbit' table\n", body->name);
         return false;
     }
 
+    // Initialize orbital elements with defaults
+    body->orbit.semi_major_axis = 0.0;
+    body->orbit.eccentricity = 0.0;
+    body->orbit.inclination = 0.0;
+    body->orbit.longitude_of_ascending_node = 0.0;
+    body->orbit.argument_of_periapsis = 0.0;
+    body->orbit.true_anomaly = 0.0;
+
+    // Parse semi_major_axis (required) or altitude (convenience)
+    toml_datum_t semi_major = toml_get(orbit_table, "semi_major_axis");
+    toml_datum_t altitude = toml_get(orbit_table, "altitude");
+
+    if (semi_major.type == TOML_FP64) {
+        body->orbit.semi_major_axis = semi_major.u.fp64;
+    } else if (altitude.type == TOML_FP64) {
+        // altitude will be added to parent radius in initialization
+        body->orbit.semi_major_axis = altitude.u.fp64;
+    } else {
+        printf("Error: Body '%s' must have either 'semi_major_axis' or 'altitude' in orbit table\n", body->name);
+        return false;
+    }
+
+    // Parse eccentricity (optional, default 0.0)
+    toml_datum_t eccentricity = toml_get(orbit_table, "eccentricity");
+    if (eccentricity.type == TOML_FP64) {
+        body->orbit.eccentricity = eccentricity.u.fp64;
+    }
+
+    // Parse true_anomaly (optional, default 0.0)
+    toml_datum_t true_anomaly = toml_get(orbit_table, "true_anomaly");
+    if (true_anomaly.type == TOML_FP64) {
+        body->orbit.true_anomaly = true_anomaly.u.fp64;
+    }
+
+    // Parse inclination (optional, default 0.0)
+    toml_datum_t inclination = toml_get(orbit_table, "inclination");
+    if (inclination.type == TOML_FP64) {
+        body->orbit.inclination = inclination.u.fp64;
+    }
+
+    // Parse longitude_of_ascending_node (optional, default 0.0)
+    toml_datum_t raan = toml_get(orbit_table, "longitude_of_ascending_node");
+    if (raan.type == TOML_FP64) {
+        body->orbit.longitude_of_ascending_node = raan.u.fp64;
+    }
+
+    // Parse argument_of_periapsis (optional, default 0.0)
+    toml_datum_t aop = toml_get(orbit_table, "argument_of_periapsis");
+    if (aop.type == TOML_FP64) {
+        body->orbit.argument_of_periapsis = aop.u.fp64;
+    }
+
     // Extract color
     toml_datum_t color = toml_get(body_table, "color");
     if (color.type != TOML_TABLE || !extract_color_from_table(color, body->color)) {
         return false;
     }
 
-    // Initialize velocity (will be calculated later)
+    // Initialize velocity and position (will be calculated later from orbital elements)
+    body->global_position = {0.0, 0.0, 0.0};
     body->global_velocity = {0.0, 0.0, 0.0};
+    body->local_position = {0.0, 0.0, 0.0};
+    body->local_velocity = {0.0, 0.0, 0.0};
     body->soi_radius = 0.0;
 
     return true;
@@ -161,6 +211,35 @@ bool load_system_config(SimulationState* sim, const char* filepath) {
         }
     }
 
+    // Validate orbital elements
+    for (int i = 0; i < body_count; i++) {
+        CelestialBody* body = &sim->bodies[i];
+
+        // Validate semi_major_axis
+        if (fabs(body->orbit.semi_major_axis) < 1e-10) {
+            printf("Error: Body '%s' has invalid semi_major_axis: %.2e (must not be zero)\n",
+                   body->name, body->orbit.semi_major_axis);
+            toml_free(result);
+            return false;
+        }
+
+        // Validate eccentricity
+        if (body->orbit.eccentricity < 0.0) {
+            printf("Error: Body '%s' has invalid eccentricity: %.3f (must be >= 0)\n",
+                   body->name, body->orbit.eccentricity);
+            toml_free(result);
+            return false;
+        }
+
+        // For elliptical orbits (e < 1), semi_major_axis must be positive
+        if (body->orbit.eccentricity < 1.0 && body->orbit.semi_major_axis <= 0.0) {
+            printf("Error: Body '%s' has elliptical orbit but non-positive semi_major_axis: %.2e\n",
+                   body->name, body->orbit.semi_major_axis);
+            toml_free(result);
+            return false;
+        }
+    }
+
     sim->body_count = body_count;
 
     strncpy(sim->config_name, filepath, sizeof(sim->config_name) - 1);
@@ -217,10 +296,6 @@ static bool load_spacecraft_from_toml(SimulationState* sim, toml_result_t result
             return false;
         }
 
-        CelestialBody* parent = &sim->bodies[craft.parent_index];
-        craft.global_position = vec3_add(parent->global_position, craft.local_position);
-        craft.global_velocity = vec3_add(parent->global_velocity, craft.local_velocity);
-
         int idx = add_spacecraft(sim, &craft);
         if (idx < 0) {
             printf("Error: Failed to add spacecraft to simulation\n");
@@ -228,6 +303,32 @@ static bool load_spacecraft_from_toml(SimulationState* sim, toml_result_t result
         }
     }
 
+    // Validate spacecraft orbital elements
+    for (int i = 0; i < sim->craft_count; i++) {
+        Spacecraft* craft = &sim->spacecraft[i];
+
+        // Validate semi_major_axis
+        if (fabs(craft->orbit.semi_major_axis) < 1e-10) {
+            printf("Error: Spacecraft '%s' has invalid semi_major_axis: %.2e (must not be zero)\n",
+                   craft->name, craft->orbit.semi_major_axis);
+            return false;
+        }
+
+        // Validate eccentricity
+        if (craft->orbit.eccentricity < 0.0) {
+            printf("Error: Spacecraft '%s' has invalid eccentricity: %.3f (must be >= 0)\n",
+                   craft->name, craft->orbit.eccentricity);
+            return false;
+        }
+
+        // For elliptical orbits (e < 1), semi_major_axis must be positive
+        if (craft->orbit.eccentricity < 1.0 && craft->orbit.semi_major_axis <= 0.0) {
+            printf("Error: Spacecraft '%s' has elliptical orbit but non-positive semi_major_axis: %.2e\n",
+                   craft->name, craft->orbit.semi_major_axis);
+            return false;
+        }
+    }
+
     printf("Loaded %d spacecraft from %s\n", craft_count, sim->config_name);
     return true;
 }
@@ -250,21 +351,70 @@ static bool parse_toml_spacecraft(toml_datum_t craft_table, Spacecraft* craft) {
     craft->mass = mass.u.fp64;
     craft->parent_index = (int)(parent_idx.type == TOML_INT64 ? parent_idx.u.int64 : (int)parent_idx.u.fp64);
 
-    toml_datum_t position = toml_get(craft_table, "position");
-    if (position.type != TOML_TABLE || !extract_vec3_from_table(position, &craft->local_position)) {
+    // Parse orbit table
+    toml_datum_t orbit_table = toml_get(craft_table, "orbit");
+    if (orbit_table.type != TOML_TABLE) {
+        printf("Error: Spacecraft '%s' missing required 'orbit' table\n", craft->name);
         return false;
     }
-    craft->global_position = craft->local_position;
 
-    toml_datum_t velocity = toml_get(craft_table, "velocity");
-    if (velocity.type == TOML_TABLE) {
-        if (!extract_vec3_from_table(velocity, &craft->local_velocity)) {
-            return false;
-        }
+    // Initialize orbital elements with defaults
+    craft->orbit.semi_major_axis = 0.0;
+    craft->orbit.eccentricity = 0.0;
+    craft->orbit.inclination = 0.0;
+    craft->orbit.longitude_of_ascending_node = 0.0;
+    craft->orbit.argument_of_periapsis = 0.0;
+    craft->orbit.true_anomaly = 0.0;
+
+    // Parse semi_major_axis (required) or altitude (convenience)
+    toml_datum_t semi_major = toml_get(orbit_table, "semi_major_axis");
+    toml_datum_t altitude = toml_get(orbit_table, "altitude");
+
+    if (semi_major.type == TOML_FP64) {
+        craft->orbit.semi_major_axis = semi_major.u.fp64;
+    } else if (altitude.type == TOML_FP64) {
+        // altitude will be added to parent radius in initialization
+        craft->orbit.semi_major_axis = altitude.u.fp64;
     } else {
-        craft->local_velocity = {0.0, 0.0, 0.0};
+        printf("Error: Spacecraft '%s' must have either 'semi_major_axis' or 'altitude' in orbit table\n", craft->name);
+        return false;
+    }
+
+    // Parse eccentricity (optional, default 0.0)
+    toml_datum_t eccentricity = toml_get(orbit_table, "eccentricity");
+    if (eccentricity.type == TOML_FP64) {
+        craft->orbit.eccentricity = eccentricity.u.fp64;
+    }
+
+    // Parse true_anomaly (optional, default 0.0)
+    toml_datum_t true_anomaly = toml_get(orbit_table, "true_anomaly");
+    if (true_anomaly.type == TOML_FP64) {
+        craft->orbit.true_anomaly = true_anomaly.u.fp64;
     }
-    craft->global_velocity = craft->local_velocity;
+
+    // Parse inclination (optional, default 0.0)
+    toml_datum_t inclination = toml_get(orbit_table, "inclination");
+    if (inclination.type == TOML_FP64) {
+        craft->orbit.inclination = inclination.u.fp64;
+    }
+
+    // Parse longitude_of_ascending_node (optional, default 0.0)
+    toml_datum_t raan = toml_get(orbit_table, "longitude_of_ascending_node");
+    if (raan.type == TOML_FP64) {
+        craft->orbit.longitude_of_ascending_node = raan.u.fp64;
+    }
+
+    // Parse argument_of_periapsis (optional, default 0.0)
+    toml_datum_t aop = toml_get(orbit_table, "argument_of_periapsis");
+    if (aop.type == TOML_FP64) {
+        craft->orbit.argument_of_periapsis = aop.u.fp64;
+    }
+
+    // Initialize position and velocity (will be calculated later from orbital elements)
+    craft->global_position = {0.0, 0.0, 0.0};
+    craft->global_velocity = {0.0, 0.0, 0.0};
+    craft->local_position = {0.0, 0.0, 0.0};
+    craft->local_velocity = {0.0, 0.0, 0.0};
 
     return true;
 }